303 lines
9.8 KiB
C
303 lines
9.8 KiB
C
/*
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* QEMU Error Objects
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*
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* Copyright IBM, Corp. 2011
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* Copyright (C) 2011-2015 Red Hat, Inc.
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Markus Armbruster <armbru@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2. See
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* the COPYING.LIB file in the top-level directory.
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*/
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/*
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* Error reporting system loosely patterned after Glib's GError.
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*
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* Create an error:
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* error_setg(&err, "situation normal, all fouled up");
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*
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* Create an error and add additional explanation:
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* error_setg(&err, "invalid quark");
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* error_append_hint(&err, "Valid quarks are up, down, strange, "
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* "charm, top, bottom.\n");
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*
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* Do *not* contract this to
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* error_setg(&err, "invalid quark\n"
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* "Valid quarks are up, down, strange, charm, top, bottom.");
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*
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* Report an error to the current monitor if we have one, else stderr:
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* error_report_err(err);
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* This frees the error object.
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*
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* Likewise, but with additional text prepended:
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* error_reportf_err(err, "Could not frobnicate '%s': ", name);
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*
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* Report an error somewhere else:
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* const char *msg = error_get_pretty(err);
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* do with msg what needs to be done...
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* error_free(err);
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* Note that this loses hints added with error_append_hint().
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*
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* Handle an error without reporting it (just for completeness):
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* error_free(err);
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*
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* Assert that an expected error occurred, but clean it up without
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* reporting it (primarily useful in testsuites):
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* error_free_or_abort(&err);
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*
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* Pass an existing error to the caller:
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* error_propagate(errp, err);
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* where Error **errp is a parameter, by convention the last one.
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*
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* Pass an existing error to the caller with the message modified:
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* error_propagate(errp, err);
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* error_prepend(errp, "Could not frobnicate '%s': ", name);
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*
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* Create a new error and pass it to the caller:
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* error_setg(errp, "situation normal, all fouled up");
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*
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* Call a function and receive an error from it:
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* Error *err = NULL;
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* foo(arg, &err);
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* if (err) {
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* handle the error...
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* }
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*
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* Call a function ignoring errors:
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* foo(arg, NULL);
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*
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* Call a function aborting on errors:
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* foo(arg, &error_abort);
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*
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* Call a function treating errors as fatal:
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* foo(arg, &error_fatal);
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*
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* Receive an error and pass it on to the caller:
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* Error *err = NULL;
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* foo(arg, &err);
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* if (err) {
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* handle the error...
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* error_propagate(errp, err);
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* }
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* where Error **errp is a parameter, by convention the last one.
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*
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* Do *not* "optimize" this to
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* foo(arg, errp);
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* if (*errp) { // WRONG!
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* handle the error...
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* }
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* because errp may be NULL!
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*
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* But when all you do with the error is pass it on, please use
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* foo(arg, errp);
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* for readability.
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*
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* Receive and accumulate multiple errors (first one wins):
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* Error *err = NULL, *local_err = NULL;
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* foo(arg, &err);
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* bar(arg, &local_err);
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* error_propagate(&err, local_err);
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* if (err) {
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* handle the error...
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* }
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*
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* Do *not* "optimize" this to
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* foo(arg, &err);
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* bar(arg, &err); // WRONG!
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* if (err) {
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* handle the error...
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* }
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* because this may pass a non-null err to bar().
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*/
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#ifndef ERROR_H
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#define ERROR_H
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#include "qapi-types.h"
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/*
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* Overall category of an error.
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* Based on the qapi type QapiErrorClass, but reproduced here for nicer
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* enum names.
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*/
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typedef enum ErrorClass {
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ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERICERROR,
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ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMANDNOTFOUND,
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ERROR_CLASS_DEVICE_ENCRYPTED = QAPI_ERROR_CLASS_DEVICEENCRYPTED,
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ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICENOTACTIVE,
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ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICENOTFOUND,
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ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVMMISSINGCAP,
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} ErrorClass;
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/*
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* Get @err's human-readable error message.
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*/
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const char *error_get_pretty(const Error *err);
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/*
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* Get @err's error class.
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* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
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* strongly discouraged.
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*/
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ErrorClass error_get_class(const Error *err);
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/*
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* Create a new error object and assign it to *@errp.
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* If @errp is NULL, the error is ignored. Don't bother creating one
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* then.
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* If @errp is &error_abort, print a suitable message and abort().
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* If @errp is &error_fatal, print a suitable message and exit(1).
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* If @errp is anything else, *@errp must be NULL.
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* The new error's class is ERROR_CLASS_GENERIC_ERROR, and its
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* human-readable error message is made from printf-style @fmt, ...
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* The resulting message should be a single phrase, with no newline or
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* trailing punctuation.
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* Please don't error_setg(&error_fatal, ...), use error_report() and
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* exit(), because that's more obvious.
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* Likewise, don't error_setg(&error_abort, ...), use assert().
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*/
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#define error_setg(errp, fmt, ...) \
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error_setg_internal((errp), __FILE__, __LINE__, __func__, \
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(fmt), ## __VA_ARGS__)
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void error_setg_internal(Error **errp,
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const char *src, int line, const char *func,
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const char *fmt, ...)
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GCC_FMT_ATTR(5, 6);
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/*
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* Just like error_setg(), with @os_error info added to the message.
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* If @os_error is non-zero, ": " + strerror(os_error) is appended to
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* the human-readable error message.
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*/
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#define error_setg_errno(errp, os_error, fmt, ...) \
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error_setg_errno_internal((errp), __FILE__, __LINE__, __func__, \
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(os_error), (fmt), ## __VA_ARGS__)
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void error_setg_errno_internal(Error **errp,
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const char *fname, int line, const char *func,
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int os_error, const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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#ifdef _WIN32
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/*
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* Just like error_setg(), with @win32_error info added to the message.
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* If @win32_error is non-zero, ": " + g_win32_error_message(win32_err)
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* is appended to the human-readable error message.
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*/
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#define error_setg_win32(errp, win32_err, fmt, ...) \
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error_setg_win32_internal((errp), __FILE__, __LINE__, __func__, \
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(win32_err), (fmt), ## __VA_ARGS__)
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void error_setg_win32_internal(Error **errp,
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const char *src, int line, const char *func,
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int win32_err, const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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#endif
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/*
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* Propagate error object (if any) from @local_err to @dst_errp.
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* If @local_err is NULL, do nothing (because there's nothing to
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* propagate).
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* Else, if @dst_errp is NULL, errors are being ignored. Free the
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* error object.
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* Else, if @dst_errp is &error_abort, print a suitable message and
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* abort().
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* Else, if @dst_errp is &error_fatal, print a suitable message and
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* exit(1).
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* Else, if @dst_errp already contains an error, ignore this one: free
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* the error object.
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* Else, move the error object from @local_err to *@dst_errp.
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* On return, @local_err is invalid.
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* Please don't error_propagate(&error_fatal, ...), use
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* error_report_err() and exit(), because that's more obvious.
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*/
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void error_propagate(Error **dst_errp, Error *local_err);
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/*
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* Prepend some text to @errp's human-readable error message.
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* The text is made by formatting @fmt, @ap like vprintf().
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*/
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void error_vprepend(Error **errp, const char *fmt, va_list ap);
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/*
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* Prepend some text to @errp's human-readable error message.
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* The text is made by formatting @fmt, ... like printf().
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*/
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void error_prepend(Error **errp, const char *fmt, ...)
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GCC_FMT_ATTR(2, 3);
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/*
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* Append a printf-style human-readable explanation to an existing error.
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* @errp may be NULL, but not &error_fatal or &error_abort.
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* Trivially the case if you call it only after error_setg() or
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* error_propagate().
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* May be called multiple times. The resulting hint should end with a
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* newline.
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*/
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void error_append_hint(Error **errp, const char *fmt, ...)
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GCC_FMT_ATTR(2, 3);
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/*
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* Convenience function to report open() failure.
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*/
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#define error_setg_file_open(errp, os_errno, filename) \
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error_setg_file_open_internal((errp), __FILE__, __LINE__, __func__, \
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(os_errno), (filename))
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void error_setg_file_open_internal(Error **errp,
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const char *src, int line, const char *func,
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int os_errno, const char *filename);
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/*
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* Return an exact copy of @err.
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*/
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Error *error_copy(const Error *err);
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/*
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* Free @err.
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* @err may be NULL.
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*/
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void error_free(Error *err);
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/*
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* Convenience function to assert that *@errp is set, then silently free it.
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*/
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void error_free_or_abort(Error **errp);
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/*
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* Convenience function to error_report() and free @err.
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*/
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void error_report_err(Error *err);
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/*
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* Convenience function to error_prepend(), error_report() and free @err.
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*/
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void error_reportf_err(Error *err, const char *fmt, ...)
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GCC_FMT_ATTR(2, 3);
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/*
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* Just like error_setg(), except you get to specify the error class.
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* Note: use of error classes other than ERROR_CLASS_GENERIC_ERROR is
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* strongly discouraged.
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*/
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#define error_set(errp, err_class, fmt, ...) \
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error_set_internal((errp), __FILE__, __LINE__, __func__, \
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(err_class), (fmt), ## __VA_ARGS__)
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void error_set_internal(Error **errp,
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const char *src, int line, const char *func,
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ErrorClass err_class, const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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/*
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* Special error destination to abort on error.
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* See error_setg() and error_propagate() for details.
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*/
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extern Error *error_abort;
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/*
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* Special error destination to exit(1) on error.
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* See error_setg() and error_propagate() for details.
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*/
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extern Error *error_fatal;
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#endif
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